Charged with murder: Amanda Hein gave birth in a sports bar bathroom and killed her newborn, prosecutors claim (Picture:YouTube)

A woman gave birth to a baby boy in the bathroom of a busy sports bar and then killed the infant by wrapping the body in a plastic bag and submerging it in a toilet tank, it has been claimed.

Amanda Catherine Hein, 26, was at Starters Pub in Bethlehem, Pennsylvania, in the US, watching a wrestling match with friends before reportedly spending about 40 minutes in the bathroom and returning to the group blood-soaked.

She insisted she was fine and went outside and smoked a cigarette before returning to her friends to continue watching the pay-per-view match, police have said.

Staff at the pub found the baby’s corpse the next morning on August 17 after complaints the toilet would not flush.

Northampton County coroner said an autopsy showed the baby was born alive and died of suffocation.

Authorities said the baby was 33 to 36 weeks and born late in the third trimester, but otherwise healthy.

Hein was tracked down and arrested after police traced a blood stain she left on the booth she was sitting at. She has admitted to giving birth and because of the age of the child, she could face the death penalty if convicted.

According to reports, the mother realised she was pregnant in May or June but did not tell anyone. No one from the all-male group of friends she was with that night knew she gave birth or even that she was carrying a child.

They told police that she had complained of back pains and spasms leading her to be excused from the group. However, they became worried and began sending her text messages. After she had allegedly killed the baby, she stayed at the bar for another hour before going home, it is alleged.